1. Field of the Invention
The present invention relates to a communication apparatus and a control method and a storage medium therefor, and more particularly, to a communication apparatus capable of performing real-time Internet facsimile communication and VoIP-based virtual voice mode facsimile communication, and a control method and a storage medium therefor.
2. Description of the Related Art
An Internet facsimile apparatus configured to be connected to IP network for execution of facsimile communication on the Internet is spreading in recent years. As a mode to realize facsimile communication via IP network, there can be mentioned a mode of ITU-T recommendation T.38 in which a facsimile signal is transferred in real-time through IFP (Internet Facsimile Protocol) packets.
In the T.38 mode, a session connection is established, peer to peer, using a SIP technique. SIP (Session Initiation Protocol) is a protocol that establishes, changes, and disconnects a session in which voice, image, text message, or the like is exchanged in application layer.
To start such a session, a facsimile apparatus exchanges information that specifies session's media type (audio, video, application, or image) with a destination apparatus. For example, a media type of audio is specified in the information to perform voice communication, whereas a media type of image or application is specified to perform communication in T.38 mode.
IP telephone, which is based on VoIP (Voice over Internet Protocol) technology for transmitting and receiving voice data in real-time on the Internet, is spreading as a service using Internet line.
Also, virtual voice mode facsimile communication based on VoIP technology comes into practical use, in which a facsimile signal is regarded as a voice signal and communicated in real-time on the Internet.
For example, a facsimile apparatus capable of executing virtual voice mode facsimile communication and T.38 mode facsimile communication on IP network is disclosed in e.g. Japanese Laid-open Patent Publication No. 2003-309701.
It should be noted that with a facsimile apparatus having a telephone function, manual transmission has heretofore been executed, in which telephone communication is switched to facsimile communication after completion of the telephone communication. However, virtual voice mode facsimile communication and T.38 mode facsimile communication are generally performed independently of each other, but are not performed in concert with each other.
As previously described, a call connection is established in a session for which a media type of voice (m=audio) is specified. At that time, it is preferable to perform communication in the T.38 mode while specifying a media type of image or application, if a destination apparatus has a T.38 communication capability. However, there is no way to determine whether the destination apparatus has a T.38 communication capability.
Accordingly, in a case that facsimile transmission is performed from a state where a connection has been established in a voice session, telephone communication is switched to virtual voice communication capable of executing facsimile transmission, with the media type of voice (m=audio) kept specified. The communication speed in facsimile communication performed in virtual voice communication mode is 33.6 kbps at maximum, which is extremely low as compared to that in T.38 communication mode.